The present invention is a disc drive having a sealed head/disc assembly, wherein the head/disc assembly includes at least one connector attached to a casing of the head/disc assembly.
Disc drives are commonly used with computers to store data on concentric tracks defined in magnetic coatings formed on magnetic discs. The discs are attached to a rotating spindle which is powered by a spindle motor. Data is written to and read from selected tracks on a disc by a read/write transducer head. The transducer head is supported by a pivotally mounted actuator which moves the transducer head across the disc in response to a current applied to an actuator coil.
Typically, the spindle, spindle motor, discs, transducers, and actuator are contained in a casing, thereby forming a head/disc assembly (HDA). Electrical signals flow between the interior of the HDA and a circuit board exterior to the HDA. The circuit board in turn is connected to a disc drive interface to allow data to flow between the disc drive and an attached computer system.
As the state of disc drive technology has advanced, the storage capacity of disc drives has increased. The distance between the concentric tracks has decreased and the density of the data stored on each track has increased. To facilitate reading and writing data at higher densities, the "flying height," or distance between the read/write transducer head and the disc surface has decreased. Today's disc drives commonly have a flying height of less than ten microinches.
A typical smoke particle, or the thickness of body oil left in a finger print, are on the order of ten times this thickness, and environment dust is even larger. Accordingly, the environment inside the HDA has to be as clean as possible.
For this reason, HDAs are assembled in clean rooms, where the level of particulates and contaminants in the environment is minimized. When the HDA is assembled, it is typically sealed to prevent particulates and contaminants from entering the HDA after it leaves the clean room.
Several methods of sealing an HDA are disclosed in the prior art. For example, Eckerd, U.S. Pat. No. 5,097,978, disclosed a base member and a cover member having specified shapes. After the cover member is placed on the base member, an adhesive strip is used to seal a clearance gap between the two members. Sleger, U.S. Pat. No. 5,021,905, also disclosed a disc drive enclosure that is sealed by viscoelastic tape.
Eckerd also addressed the problem of outgassing. Outgassing occurs as a material ages, and various gases are released from the material. Outgassing is very common when using polymer based gaskets, sealers, and caulking. Accordingly, disc drive designer have had to search for sealing materials having minimal outgassing, and they have had to design casings where the physical construction of the casing provided for the released gases to vent away from the HDA.
Another problem encountered by disc drive designers was routing the electrical connections from the actuator located in the interior of the HDA to a circuit board located exterior to the HDA. Typically, a thin, flexible circuit is used to deliver signals to and remove signals from the actuator. The flexible circuit allows the actuator to move freely while maintaining the electrical connections to the actuator. In the prior art, a common method of routing signals to the exterior of the HDA was to position the flexible circuit between two pieces of the casing. After the pieces of the casing were fastened, viscoelastic adhesive tape was applied to the interface between the casing pieces, including the portion of the interface along which the flexible circuit was routed. However, routing the electrical connection by this method did not provide a tight seal, and inevitably air would leak around the flexible circuit.